MIME-Version: 1.0
References: <ZgQeJDcxB9zYJKIt@ip-10-97-1-34.eu-west-3.compute.internal>
 <CALj2ACX1bdaX2gf5ttwk3buiDrgZVV=vM6S1SQKf=Sxhj1HkzQ@mail.gmail.com>
 <CAA4eK1JU14-Fz3Ttx_wy=vzDaeTSv=umt7sC3N+4k2aYcdk4=w@mail.gmail.com>
 <CALj2ACWOz0tEY2vi3OneittGj9+yrQ9A6+6YYb1Cj7L_QrdMVg@mail.gmail.com>
 <CAD21AoAd0BX0L17YxSCbSNbj=3V7dvLVGY0WhwLHAt724rNCZA@mail.gmail.com>
 <ZgulmKzdqxuBuhCU@ip-10-97-1-34.eu-west-3.compute.internal>
 <CAJpy0uBthb-RG=Xg+mM-G6Xy01JLcBsizJuz+xbti08qP_W7AQ@mail.gmail.com>
 <CALj2ACVfDBcbybgyga7ia_KiQPAfEi_3=VDOGf2VU8RkJZSQpw@mail.gmail.com>
 <Zg0QgarM9UlRutLw@ip-10-97-1-34.eu-west-3.compute.internal>
 <CALj2ACUmp-F+irHYfNhmo_9yaCo7aGi7ZB20KQcDR3S9eT56hg@mail.gmail.com>
 <Zg1WqRS/gQrLG2vl@ip-10-97-1-34.eu-west-3.compute.internal>
 <CALj2ACUBiRLHF7VYD-0nYVHSvVBSCQ_5OMbP4tE8Ys_rpvQ--A@mail.gmail.com>
 <CAD21AoATS=8+izerKERjoNCrakk+cw=YvtvUsgiVcNE1GENLog@mail.gmail.com> <CALj2ACVFhnCq3oPREE0i24mPArCjqbvtbF9QDJyw+NuiAZOoiA@mail.gmail.com>
In-Reply-To: <CALj2ACVFhnCq3oPREE0i24mPArCjqbvtbF9QDJyw+NuiAZOoiA@mail.gmail.com>
From: Masahiko Sawada <sawada.mshk@gmail.com>
Date: Thu, 4 Apr 2024 17:01:30 +0900
Message-ID: <CAD21AoBF_XjJqNV8bf838fpZHR==ANsP98tFF4Ei1VKKLYxZQw@mail.gmail.com>
Subject: Re: Introduce XID age and inactive timeout based replication slot invalidation
To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, shveta malik <shveta.malik@gmail.com>, 
	Amit Kapila <amit.kapila16@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://www.postgresql.org/message-id/CAD21AoBF_XjJqNV8bf838fpZHR%3D%3DANsP98tFF4Ei1VKKLYxZQw%40mail.gmail.com>
Precedence: bulk

On Thu, Apr 4, 2024 at 1:34=E2=80=AFPM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Thu, Apr 4, 2024 at 9:42=E2=80=AFAM Masahiko Sawada <sawada.mshk@gmail=
.com> wrote:
> >
> > @@ -1368,6 +1416,7 @@ ShutDownSlotSync(void)
> >     if (SlotSyncCtx->pid =3D=3D InvalidPid)
> >     {
> >         SpinLockRelease(&SlotSyncCtx->mutex);
> > +       update_synced_slots_inactive_since();
> >         return;
> >     }
> >     SpinLockRelease(&SlotSyncCtx->mutex);
> > @@ -1400,6 +1449,8 @@ ShutDownSlotSync(void)
> >     }
> >
> >     SpinLockRelease(&SlotSyncCtx->mutex);
> > +
> > +   update_synced_slots_inactive_since();
> >  }
> >
> > Why do we want to update all synced slots' inactive_since values at
> > shutdown in spite of updating the value every time when releasing the
> > slot? It seems to contradict the fact that inactive_since is updated
> > when releasing or restoring the slot.
>
> It is to get the inactive_since right for the cases where the standby
> is promoted without a restart similar to when a standby is promoted
> with restart in which case the inactive_since is set to current time
> in RestoreSlotFromDisk.
>
> Imagine the slot is synced last time at time t1 and then a few hours
> passed, the standby is promoted without a restart. If we don't set
> inactive_since to current time in this case in ShutDownSlotSync, the
> inactive timeout invalidation mechanism can kick in immediately.
>

Thank you for the explanation! I understood the needs.

Regards,

--=20
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com